<!DOCTYPE html>

<html>
<head>
    <style>
        body {
            height: 2000px;
            width: 2000px;
        }
        
        .fixed {
            position: fixed;
            background-color: gray;
        }
        
        #top, #bottom {
            width: 100%;
            left: 0;
            height: 100px;
        }

        #left, #right {
            width: 100px;
            top: 0;
            height: 100%;
        }

        #top { top: 0; }
        #bottom { bottom: 0; }

        #left { left: 0; }
        #right { right: 0; }
    </style>
    <script>
        if (window.testRunner) {
            testRunner.dumpAsText();
            testRunner.waitUntilDone();
        }

        function doAfterZooming()
        {
            // Zooming may scroll the view away from the origin.
            window.scrollTo(0, 0);

            if (window.internals) {
                document.getElementById('scrolling-tree').textContent = internals.scrollingStateTreeAsText();
                document.getElementById('layer-tree').textContent = internals.layerTreeAsText(document);
            }
            
            if (window.testRunner)
                testRunner.notifyDone();
        }

        function getUIScript()
        {
            return `(function() {
                uiController.zoomToScale(2, function() {
                    uiController.uiScriptComplete(uiController.zoomScale);
                });
            })();`;
        }

        function doTest()
        {
            if (!window.testRunner)
                return;

            testRunner.runUIScript(getUIScript(), function(zoomScale) {
                doAfterZooming();
            });
        }
        
        window.addEventListener('load', doTest, false);
    </script>
</head>
<body>
    <div id="top" class="fixed"></div>
    <div id="bottom" class="fixed"></div>
    <div id="left" class="fixed"></div>
    <div id="right" class="fixed"></div>
<pre id="scrolling-tree">Scrolling tree goes here</pre>
<pre id="layer-tree">Layer tree goes here</pre>
</body>
</html>